The present invention relates to a method of processing a nanotube, and more particularly to a method of processing a nanotube, which is suitable for cutting the nanotube and for forming a top of the nanotube.
A single-walled carbon nanotube has an extremely fine structure of nanometer order. Properties of the single-walled carbon nanotube have been on the investigation. The research and developments of the single-walled carbon nanotube for application have been active. The single-walled carbon nanotube comprises a single layer of graphite hexagonal network. An electron structure largely varies depending upon a diameter of the tube and chiral angle, for which reason the electrical conductivity of the carbon nanotube varies between a conductivity of a metal and a conductivity of a semiconductor, and further the carbon nanotube exhibits a property similar to one-dimensional electric conduction.
The carbon nanotube may be applied to a field emitter. This field emitter has been known and is disclosed in (1) W. A. de Heer, A. Chatelain, and D. Ugarte, Science 270, 1179 (1995); (2) A. G. Rinzler, J. H. Hafner, P. Nikolaev, L. Lou, S. G. Kim, D. Tomanek, P. Nordlander, D. T. Colbert, and R. E. Smalley, Science, 269, 1550 (1995); (3) P. G. Collins and A. Zettl, Appl. Phys. Lett., 69, 1969 (1996); (4) Q. H. Wang, T. D. Corrigan, J. Y. Dai, P. R. H. Chang, and A. R. Krauss, Appl. Phys. Lett., 70, 3308 (1997); (5) Y. Saito, K. Hamaguchi, T. Nishino, K. Hata, K. Tohji, A. Kasuya, and Y. Nishina, Jpn. J. Appl. Phys., 36, L1340 (1997); (6) J-M. Bonard, J-P. Salvetat, T. Stockli, W A. de Heer, L. Forro, and A. Chatelain, Appl. Phys. Lett., 73, 918 (1998).
The sharpness of the top of the field emitter of the carbon nanotube emphasizes the field effect and realizes the good characteristic of the field emission.
No practicable method of operating the nanotube tip and controlling the same has been established, for which reason the conventional carbon nanotube is extremely low in probability of having an optimum directionality and serving as a useful electron emitter. As shown in (7) Y Zhang and S. Iijima, Philos. Mag. Lett., 78, 139 (1998), the most of the manufactured single-walled carbon nanotube is large in aspect ratio or is slender and further is curved, for which reason it is difficult to practice the single-walled carbon nanotube.
It is actually difficult that the plural nanotube tips are arranged in the same direction and the plural nanotubes are aligned along a single line. As shown in the above literature (7), it is actually difficult to evaluate the nanotube tip with a probe.
In order to have solved the above problem, there was proposed a method of cutting the single carbon nanotube by an oxidation using nitric acid, an acid mixed with nitric acid or sulfuric acid. The cutting method is disclosed in (8) K. B. Shelimov, R. O. Esenaliev, A. G. Rinzler, C. B. Huffman, and R. E. Smalley, Chem. Phys. Lett., 282, 429 (1998); (9) J. Liu, M. J. Casavant, M. Cox, D. A. Walters, P. Boul, W. Lu, A. J. Rimberg, K. A. Smith, D. T. Colbert, and R. E. Smalley, Chem. Phys. Lett., 303, 125 (1999); (10) Z. Shi, Y. Lian, F. Liao, X. Zhou, Z. Gu, Y. Zhang, and S. Iijima, Solid State Comm., 112 (1999) 35.
The above cutting method for cutting the single-walled carbon nanotube is incapable of cutting, at a specified site, the single-walled carbon nanotube. Namely, the above cutting method is unable to specify the cutting site of the single-walled carbon nanotube. Since the above cutting method is the chemical wet process using acid such as nitric acid and sulfuric acid, the acid provides undesirable influence to the manufacturing process. The above conventional cutting method is unsuitable for forming the micro device.
In the above circumstances, it had been required to develop a novel method of processing a nanotube free from the above problem.